This invention relates methods and compositions for development or enhancement of flavor in foods in which flavor develops from the action of enzymes and/or bacteria on flavor precursors. The invention is advantageous in particular for foods manufactured to have reduced fat or to be fat free, in particular for filled cultured dairy products that have a fat substitute. The methods include altering the sequence of steps generally used to manufacture some filled products so that all the aqueous protein composition is homogenized.
Flavor is an elusive, complex, yet necessary component of foods. Some of the most distinctive and popular flavors characterize cultured dairy products. Therefore, it is a challenge to produce a reduced fat cultured dairy product that has a flavor equal to its full fat counterpart. Without flavor, these products are unacceptable to consumers, even though they may fulfill consumers' requests for healthier products.
One category of healthier products is a group of foods characterized as reduced fat, low fat, or fat free. Although these food products have been successfully manufactured, for many of these products, flavor is unsatisfactory to consumers when compared to the flavor of the comparable product that contains fat at natural levels. This is a particular problem for dairy products which rely in part on milk fat for flavor.
Milk fat provides flavor preferred by consumers. Development of flavors in dairy products such as cheese with a milk fat component is complex, and not well understood (Chapman and Sharpe, 1981). For example, flavor development in yogurt milk is believed to involve many processes, including fermentation of milk sugar, enzymatic and chemical reactions involving peptides and amino acids as precursors, for fat degradation (Table V, p. 265 Robinson, 1981).
Unfortunately, problems have arisen in attempts to preserve the milk fat flavor in dairy products designed to meet trends in consumers eating patterns based on health-conscious avoidance of high fat and/or high cholesterol foods. As pointed out in Chapman and Sharpe (1981), ". . . Cheddar cheese made from skim milk has no Cheddar flavor at all." Although the reason for this flavor loss is not clear, removal of flavor precursors during processing is a potential factor.
Milk fat flavor is believed to be an amalgamum of many components including short-chain fatty acids (C.sub.4 to C.sub.10), lactones, methyl ketones, aldehydes, esters, alcohols, hydrocarbons, aromatic compounds, indole, methyl indole, phenolic compounds, and dimethyl sulfide (Kaylegian et al., 1993). Therefore, seeking a solution to flavor loss or flavor degradation, was not expected to be straightforward. Focusing on a single factor or set of factors would be thought too simplistic to improve flavor significantly.
Problems in using modified milk fat in foods are reviewed by Kaylegian et al. (1993). Expanded use of milk fat in foods, where it can contribute substantially to flavor and quality, is frequently inhibited because of functional incompatibilities with other ingredients. Although various processes modify milk fat to create specialty milk fat ingredients, milk fat functionality cannot always be predicted in complex food systems.
Consumers have indicated they would eat more lower fat products made with fat replacers than traditionally made products if they liked the taste. (Bruhn et al., 1992). Recognizing the importance of flavor to the consumer, attempts have been made to improve the flavor of reduced fat, low fat, or fat free dairy products, but there still remains a need for a simple, reproducible, relatively inexpensive method to create flavors that are acceptable to consumers, without defeating the purpose of manufacturing a healthy product.
A possible solution to flavor loss is to add flavor to the end product to replace that lost during processing. However, attempts to simulate milk flavors synthetically using fatty acids have not been successful. (Ha and Lindsay, 1993.) The flavor of milk fat is complex and difficult to duplicate synthetically because many of the flavor compounds in milk fat exist in the bound or precursor state and are released upon heating (Kaylegian, et al. 1993).
Other suggested reasons that the quality of reduced fat cultured dairy products does not compare favorably with full fat counterparts, include possible degradation of milk protein in producing a "filled dairy product."
A filled dairy product is one in which all or part of the dairy fat is removed and replaced by a vegetable sourced oil ("filled milk" or "filled cream"). The oil is either digestible (for example, soy bean oil) or undigestible (for example, polyol fatty acid polyester (PFAP)), a synthetic fat, or any imitation fat. Filled dairy products require the production of a filled milk or filled cream, which is subsequently diluted to a standardized fat level (for example, in a cheese vat). Subsequent manufacturing steps depend on the product and are well-known to those of skill in the art for full fat products (for example, for cheese). The high shear homogenization step in the manufacturing process is said to affect product quality, at least for certain cheeses. Davis (1965) teaches that homogenization to reduce fat droplet size from 4 microns to 1 micron will increase viscosity and yield a smoother curd. Additionally, Davis cautions that homogenization changes the physical properties of milk casein which leads to a weaker rennet curd.
A U.S. patent relating to cheese products, Bodenstein et al. (U.S. Pat. No. 5,080,912) teaches that it is essential that a substantial amount of milk protein not be impaired by the effects of homogenization (high shear) if high quality filled cheese products are to be produced. Bodenstein teaches not subjecting all the milk protein to high shear homogenization for manufacture of cheese products with polyol fatty acid polyesters.
The present invention addresses the problem of inferior product quality, in particular when the product is a filled cultured dairy product.